[ALOY-221] Improve error output from ti.alloy compiler plugin for all python versions

The subprocess.check_output method is currently used by the ti.alloy compiler plugin to execute the appropriate commands and output error information, if necessary. While this works well and gives us good error logs, it only works for python 2.7+, where in its current state, Titanium supports 2.6+. There is a fallback function that is executed in case the developer does not have 2.7+ installed, `. This method, unfortunately, does not give the full error log subprocess.check_output` does. We need to implement a method in the ti.alloy compiler plugin that allows for solid error output on python 2.6+.